Ring Shaped Swelling on Penis

Hello

I am a 30 year old, healthy male. I have developed this swelling under the head of my penis for the past year or so. At first, I thought it was just an inflammation but it has not gone away. The swelling / inflammation is not painful and is visible whether I am erect or not. The swelling is under the head of my penis and is almost in a ring shape. It is at times painful when I am erect but does not hurt during urination or ejaculation. I am currently not sexually active and havent been in a sexual relationship for the past six years so I think its not a STD as I developed this condition years after I discontinued sex. I would be grateful if someone could recommend any diagnosis and cure or recommend whether I should consult a urologist or a dermatologist?